WIP: support formatting in ORAS commands

[qweeah]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Please check the following list:

• Does the affected code have corresponding tests, e.g. unit test, E2E test?
• Does this change require a documentation update?
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have an appropriate license header?

[codecov]

Codecov Report

Attention: 89 lines in your changes are missing coverage. Please review.

Comparison is base (616c3e1) 81.73% compared to head (97c58d9) 82.14%.

Files	Patch %	Lines
cmd/oras/internal/display/pull.go	77.02%	22 Missing and 12 partials ⚠️
cmd/oras/internal/display/pack.go	75.75%	11 Missing and 5 partials ⚠️
cmd/oras/root/manifest/fetch.go	67.44%	10 Missing and 4 partials ⚠️
cmd/oras/root/discover.go	83.33%	5 Missing and 4 partials ⚠️
cmd/oras/root/pull.go	72.22%	4 Missing and 1 partial ⚠️
cmd/oras/root/push.go	69.23%	2 Missing and 2 partials ⚠️
cmd/oras/internal/metadata/pull.go	85.00%	2 Missing and 1 partial ⚠️
cmd/oras/internal/metadata/mappable.go	92.59%	2 Missing ⚠️
cmd/oras/root/attach.go	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #7      +/-   ##
==========================================
+ Coverage   81.73%   82.14%   +0.40%     
==========================================
  Files          68       77       +9     
  Lines        3806     4039     +233     
==========================================
+ Hits         3111     3318     +207     
- Misses        487      503      +16     
- Partials      208      218      +10     

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